基于缓蓄快放系统的西安市护城河水质改善方法研究

Research on Water Quality Improvement Method Based on Slowly-Stored and Quickly-Released System in Xi'an Moat

研究缓蓄快放系统,探索水资源短缺地区的河流水动力提升方法及其对水质影响规律。以西安市护城河南西线为研究区,根据护城河现状水质与水动力数据,利用MIKE21构建了西安市护城河水动力-水质耦合模型。依护城河现有坝体设计蓄水闸门,模拟河道上游快速泄水对下游河道的冲淤能力,探究不同蓄水高度和不同水质条件快速泄水对护城河水动力和水质的影响规律。基于MIKE21的数值模拟结果表明,不同蓄水高度对水体的水动力特性影响显著,蓄水水质对污染物浓度具有显著影响。基于MIKE21的西安市护城河水动力-水质耦合模型模拟结果表明采用1 m蓄水高度与Ⅲ类水补给相结合的工况可以最大程度实现护城河水体的水质、水动力改善。西安市护城河采用符合地表水Ⅲ类的补水水源,通过提升护城河水动力的方式可以有效改善西安市护城河水质状态。

The slowly-stored and quickly-released system was studied to explore the method of optimizing the hydrodynamic force of rivers in arid regions and reveal its effect on water quality.The south-west tributary of Xi'an moat was defined as the study area.A hydrodynamic force-water quality coupling model of the moat was built based on the collected data of current water quality and hydrodynamic force by using MIKE21.In the coupling model,the impounding gate was designed based on the dam body of the moat to simulate the scouring and silting capacity of the lower reaches caused by rapid discharge from the upper reaches of the channel.The influence law of rapid discharge at different water levels and water quality conditions on hydrodynamics and water quality of the moat was studied.The numerical simulation results from MIKE21 show that water level has a significant influence on the hydrodynamic force,and water quality has a significant influence on the pollutant concentration.The simulation results of the hydrodynamic force-water quality coupling model of the moat show that the working condition with a 1-meter water level and classⅢinlet water quality can greatly improve the water quality and hydrodynamic force of Xi'an moat.By using the water reaching the standard of the classⅢinlet water quality as the supply source,the water quality of Xi'an moat can be effectively improved by enhancing the hydrodynamic force of the moat.